Characterizing wing tears in common pipistrelles (Pipistrellus pipistrellus): investigating tear distribution, wing strength, and possible causes

Bats have large, thin wings that are particularly susceptible to tearing. Anatomical specializations, such as fiber reinforcement, strengthen the wing and increase its resistance to puncture, and an extensive vasculature system across the wing also promotes healing. We investigated whether tear positioning is associated with anatomy in common pipistrelles (Pipistrellus pipistrellus). Wing anatomy was described using histological techniques, imaging, and material testing. Tear information, including type, position, time in rehabilitation, and possible causes, was collected from rehabilitators of injured bats across the United Kingdom. Results suggest that the position of the plagiopatagium (the most proximal wing section to the body), rather than its anatomy, influenced the number, location, and orientation of wing tears. While material testing did not identify the plagiopatagium as being significantly weaker than the chiropatagium (the more distal sections of the wing), the plagiopatagium tended to have the most tears. The position of the tears, close to the body and toward the trailing edge, suggests that they are caused by predator attacks, such as from a cat (Felis catus), rather than collisions. Consistent with this, 38% of P. pipistrellus individuals had confirmed wing tears caused by cats, with an additional 38% identified by rehabilitators as due to suspected cat attacks. The plagiopatagium had the lowest number of blood vessels and highest amounts of elastin fibers, suggesting that healing may take longer in this section. Further investigations into the causes of tears, and their effect on flight capabilities, will help to improve bat rehabilitation

Aerogel Processing

International audienceOne of the problems largely commented in the sol-gel science is how to make large bodies, because gels tend to crack during drying. The drying stresses are attributed to capillary phenomena and differential strain which result from a pressure gradient in the pore liquid. By the supercritical drying (SCD), the capillary stresses are eliminated and monolithic aerogel can be obtained. This chapter focuses on silica aerogel, the most studied aerogel. It presents an overview of the supercritical drying techniques, but also some of the remarkable aerogel properties (optical, mechanical, thermal and acoustical, etc.) with respect to its peculiar microstructure. The chapter briefly presents other kinds of aerogels (oxides and chalcogenideaerogels, composite aerogels, organic aerogels, etc.) and a panel of potential applications